High frequency electromagnetic noise and radiated emissions can travel along electrical cables and through housing apertures that receive cable connectors for entry into otherwise shielded housings. For example, previously known electronic control modules that include microprocessor circuitry for controlling passenger vehicle operations often include processing circuits that must be shielded from strong electrical currents and voltages that are generated by power supplies under the control of or in response to the processing being performed in the module. The module generally includes a housing cover over the circuitry, and the housing cover is often made of metal to form a shield that prevents the circuitry from being affected by stray radiation. Nevertheless, the electrical connections that must be made to the circuits carried within the housing provides access for stray radiation to leak into the housing and affect the operation of the circuitry carried within the housing.
In previously known control modules, the circuitry is often carried on a cold plate, particularly designed to cool the circuitry in which it is carried. However, while the circuits are carried upon the cold plate, the housing covers are also carried by the cold plate, and electrical connectors to the circuits are provided through openings in the housing wall. Although shields have been developed to reduce entry of stray radiation in these openings, such structures often require the manufacture and assembly of numerous parts and proper installation over the conductors and the opening in order to properly shield the interior of the housing from the stray radiation. For example, the conductors may be carried by a connector with a conductive shield and specially insulated supports for the conductor so that the conductive shield mounted in a grounded connection with the remaining housing cover to minimize the flow of EMI, including RFI, into the housing. As a result, the special shields may be particularly difficult to install and can substantially increase the expense of the housing structure.
Moreover, connectors which extend through openings in the housing cover substantially complicate the assembly and disassembly of the electronic control module. In particular, since the connector carries conductors that must be wired to circuits carried by the cold plate, the wire length limits the displacement of the housing from the cold plates and obstructs repair of the circuitry unless the wiring is detached from the circuit. Therefore, the previously known control module housing structures are substantially more difficult to assemble and to disassemble for repair. Often, to obtain access to the control circuitry carried on the cold plate, the connector must be disassembled from the housing cover. However, since displacement of the housing cover is limited by the length of the conductors carried by the connector held in the housing cover, such disassembly must be performed in a restricted access area. As a result, it is often necessary to loosen the cover from the cold plate, displace the cover to the extent possible against the restraint of the conductors connected to the circuits, and disconnect the conductors from the circuits before it is possible to further displace the housing away from the cold plate. Thus, both the assembly and the disassembly of such control module housings can be extremely difficult, particularly where small I.C.'s or circuit boards are installed within the module housing walls. Alternatively, the connector must be constructed in multiple pieces to permit easy removal of the connector from the housing walls before the housing cover is removed from the cold plate.
Another known feature of previous control module housing construction comprises separation of the high power connectors and circuits from the low power connectors and circuits by the cold plate. In particular, the high power conductors connect to circuits mounted on one side of the cold plate, and are separated by the cold plate from the low power connectors and their connections with circuits mounted on the opposite side of the cold plate. However, while this avoids interference within the housing, each side of the cold plate has a separate cover that carries a separate connector. As a result, the difficulties of removing the housing covers carrying the connectors, and the problems discussed above related thereto, are compounded by such an arrangement.
A further improvement to reduce the difficulty of accessing the circuits in the control module is provided by securing the high power connector directly to the cold plate and unattached to the top cover. However, such a construction provided a direct path for the EMI to radiate into or out of the electronic box, and required environmental sealing between the high power connector and the cold plate, between the cover and the cold plate, and between the connector and the cover. Since each of these materials may react differently to environmental conditions, the problems of sealing are exacerbated by such a construction as numerous non-planar interfaces and multiple open-ended gaskets or seals are assembled.
Another attempt to avoid these problems involved the redesign of the top cover to include a first side wall portion that carried both the high power and low power connectors, and a separate top cover plate to form a housing on one side of the cold plate. This multiplication of housing parts had to be repeated in module constructions where both sides of the cold plate were used to support the circuitry. Moreover, the high side wall structure limits access to the conductor connections with the circuits in the module, and requires the circuits to be assembled and the conductors to be secured, in a five-sided enclosure that complicates both assembly and repair by inhibiting movement and manipulation of tools and parts in the bounded area. In particular, specially designed or configured tools may be required to reach the components or conductors to be installed or assembled in view of the limited work area defined between the raised side walls.